Spironolactone Ameliorates Cochlear Implant Induced Endolymphatic Hydrops

Area of Science:

• Otolaryngology
• Neurosurgery
• Pharmacology

Background:

• Endolymphatic hydrops (EH) is a recognized complication following cochlear implant (CI) surgery in both humans and animal models.
• The potential therapeutic role of mineralocorticoid steroid antagonists in managing post-CI EH remains largely unexplored.

Purpose of the Study:

• To investigate the efficacy of spironolactone, a mineralocorticoid receptor antagonist, in mitigating EH post-CI.
• To evaluate the electrophysiological consequences of spironolactone administration on auditory function after CI.

Main Methods:

• Adult guinea pigs received cochlear implantation with a dummy electrode and were observed for 2, 7, or 28 days.
• Auditory function was assessed using electrocochleography, and EH was quantified via thin-sheet laser imaging microscopy.
• Spironolactone or a control solution was administered orally starting immediately before surgery.

Main Results:

• Spironolactone treatment significantly reduced EH in the cochlea by 7 days post-implantation.
• Compound action potential (CAP) thresholds were elevated early post-implantation but largely recovered by 28 days, with no significant treatment effect.
• No differences in CAP amplitude growth were observed between spironolactone-treated and control groups.

Conclusions:

• Antagonism of mineralocorticoid receptors with spironolactone can suppress EH in the week following cochlear implantation.
• EH reduction did not correlate with changes in hearing preservation or indicate synaptopathy.
• Early post-implantation EH does not appear to negatively impact residual hearing based on electrophysiological evidence.